Popular variations of Blackjack offer different rules that change gameplay and strategy. For instance, "Spanish 21" removes the 10 cards from the deck, making it more challenging to hit 21, but it offers better player-friendly rules like bonuses for certain hand combinations. "Blackjack Switch" allows players to swap cards between two hands, giving more control but often resulting in lower payouts for a natural blackjack. "Pontoon" has similar gameplay but uses different terms and includes a rule where both dealer cards remain face down until the end. These variations add twists to traditional Blackjack, altering both the house edge and player experience.